Burglar-alarm



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O. CONRAD. BURGLAR ALARM.

No. 289,624. Patented Dec. 4,1883. l

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WITNESSES:

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-nrrnn STATES PATENT OFFICE.

OSBOItN CONRAD, OF PHILADELPHIA, PENNSYLVANIA.

BURGLAR-ALARM.

SPECIFICATION forming part of Letters Patent No. 289,624, dated December 4, 1883,

' Application filedFebruary 27,1883. (Modem To all whom/it may concern:

Be it known that I, OSBORN CONRAD, a citizen of the United States, residing in the city and county of Philadelphia, State of Pennsylvania, have invented. anew and use ful Improvement in Burglar-Alarms, which improvement is fully set forth in the following specification and accompanying drawings, in which- Figure 1 is a view of the interior of a burglar-alarm embodying my invention, taken from the bottom thereof. Figs. 2 and 3 are views of opposite sides thereof. Fig. 4 is a vertical section in line x m, Fig. 2.

Similar letters of reference indicate corresponding parts in the several figures.

My invention consists of a burglar-alarm formed of a box which is adapted to be placedin proximity to the lower end of a door, and provided on its outside with an arm which, when the door is opened, is caused to release the holding mechanism of an alarm, thus avoiding the construction of the box in two parts and the employment of a spring to hold the upper weighted part in elevated position,

as will be hereinafter fully set forth and definitely claimed.

Referring to the drawings, A represents a box, preferably of wedge shape, the upper side being diagonal. Within the box is placed a gong, B, and clock mechanism having an escapement-wheel, C, escapement-lever or Verge D, and hammer E, as well known in alarms of this class.

F represents an arm which is pivotedto the side of the box, at what may be termed the pointed end of the box, and has connected with it a tripping-piece, G, which is passed through a slot, a, in the side wall of the box, and so disposed that when the arm F is elevated said piece comes in contact with the escapement-lever or verge, it, however, being evident that the piece may be made to engage with the escapement-wheel or with the hammer.

The operation is as follows: When the spring of the clock movement is properly wound, the arm F is raised, whereby the piece G holds the escapement-lever and prevents operation of the alarm. The box is then set within an apartment, on the floor, adjacent to the lower edge of the door to be guarded. Should the door he opened, it will bear against the arm F and lower the said arm, and cause the piece G to leave the escapement-lever, which, thus being tripped, is free to operate, and an immediate operation of the alarm is occasioned. The extent of elevation of the arm F is limited by the top wall of the slot a, thus also preventing displacement of said arm.

The use of the alarm is not limited to doors, as it may be applied to'other placessuch as adjacent to the meeting rails of windowsashes-so as to be operated by the raising or lowering of the sashes.

In order to hold the box securely in position on the floor, the under side thereof is provided with a spur, H, which takes firm hold of the floor and prevents shifting of the box.

I am aware that it is not new to make a burglar-alarm of a box of two parts hinged together, the upper part being adapted to be raised, so that when said part is depressed the alarm is sounded; but in my case I use but a single box, thus simplifying the construction and reducing the expense, and the arm F, owing to its upper exposed edge, is more sensitive to the action of the door than the broad top of the movable part of the aforesaid box. Furthermore, in said alarm the upper part is heavy and necessitates a spring to hold it elevated. This requires more force on the door to start the alarm and immediately indicates to the burglar the existence of an obstacle, and causes him to adopt some other course; but in my case the light and simple arm F is held elevated by slight friction, which is quickly overcome; hence the sensitiveness of action of said arm and immediate release of the alarm mechanism.

What is here admitted as in existence is shown in the Letters Patent No. 151,526, grantedto Robert N. Wetherill, June 2, 1874, which is hereby disclaimed.

Having thus described my invention, What I claim as new, and desire to secure by Letters said slot a to the alarm mechanism in the Patent, isbox, substantially as and for the purpose set The burglaralarm boX A, provided with a fort slot, a, in its side wall, in combination with OSBORN CONRAD. 5 the arm F, which is pivoted to the outside Witnesses:

of said box, and the tripping-piece G, which WM. M. MOKNIGHT, is secured to said arm and passes through JOHN A. XVIEDERsHEIM. 

